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Computation of Stress Distribution in Hydraulic Horizontal Propeller Turbine Runner Based on fluid-structure interaction Analysis

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ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2020年第11期45卷 9325-9337页

作者： Waqas, Muhammad Ahmad, Naseer Pakistan Inst Engn & Technol Dept Mech Engn Multan Pakistan Univ Engn & Technol Dept Mech Engn Lahore Pakistan

In the hydro-turbine operation, the kinetic energy of flowing fluid is converted into mechanical energy. In the turbine operation, fluid induces hydraulic load that not only provides a useful mechanical driving torque on the turbine shaft but also causes deformation in turbine components and stress distribution that might induce a structure failure. Structural failure in turbine component decreases performance as well as increases the maintenance cost of hydro-turbines. In this paper, fluid-structure interaction model is used to investigate the stress distribution and total deformation of hydraulic horizontal propeller turbine runner (HHPTR) with different flow velocities, blade widths and blade wrap angles. The results showed that the effects of blade wrap angles and blade width significantly influence the performance and structural strength of the HHPTR. Maximum turbine performance was observed at blade wrap angle of 100 degrees and blade width of 2 mm. It was also found that the maximum value of equivalent stress near the runner hub is 59.54 MPa at blade wrap angle 100 degrees. Similarly, the maximum value of total deformation in HHPTR is 0.7689 mm near the runner blade edges at blade wrap angle 60 degrees.

关键词： fluid-structure interaction Propeller turbine Blade wrap angle Runner blades Computational fluid dynamics Finite element method

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Existence of a weak solution to the fluid-structure interaction problem in 3D

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JOURNAL OF DIFFERENTIAL EQUATIONS 2020年第4期268卷 1495-1531页

作者： Trifunovic, Srdan Wang, Ya-Guang Shanghai Jiao Tong Univ Sch Math Sci Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ Sch Math Sci MOE LSC Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ SHL MAC Shanghai 200240 Peoples R China

We study a nonlinear fluid-structure interaction problem in which the fluid is described by the three-dimensional incompressible Navier-Stokes equations, and the elastic structure is modeled by the nonlinear plate equation which includes a generalization of Kirchhoff, von Karman and Berger plate models. The fluid and the structure are fully coupled via kinematic and dynamic boundary conditions. The existence of a weak solution is obtained by designing a hybrid approximation scheme that successfully deals with the nonlinearities of the system. We combine time-discretization and operator splitting to create two subproblems, one piece-wise stationary for the fluid and one in the Galerkin basis for the plate. To guarantee the convergence of approximate solutions to a weak solution, a sufficient condition is given on the number of time discretization sub-intervals in every step in a form of dependence with number of the Galerkin basis functions and nonlinearity order of the plate equation. (C) 2019 Elsevier Inc. All rights reserved.

关键词： fluid-structure interaction Incompressible viscous fluid Nonlinear plate Three space variables Weak solution

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fluid-structure interaction Analysis of Perfusion Process of Vascularized Channels within Hydrogel Matrix Based on Three-Dimensional Printing

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POLYMERS 2020年第9期12卷 1898页

作者： Yang, Shuai Shi, Jianping Yang, Jiquan Feng, Chunmei Tang, Hao Nanjing Normal Univ Sch Elect & Automat Engn Nanjing 210023 Peoples R China Nanjing Normal Univ Jiangsu Key Lab Printing Equipment & Mfg 3D Nanjing 210042 Peoples R China

The rise of three-dimensional bioprinting technology provides a new way to fabricate in tissue engineering in vitro, but how to provide sufficient nutrition for the internal region of the engineered printed tissue has become the main obstacle. In vitro perfusion culture can not only provide nutrients for the growth of internal cells but also take away the metabolic wastes in time, which is an effective method to solve the problem of tissue engineering culture in vitro. Aiming at user-defined tissue engineering with internal vascularized channels obtained by three-dimensional printing experiment in the early stage, a simulation model was established and the in vitro fluid-structure interaction finite element analysis of tissue engineering perfusion process was carried out. Through fluid-structure interaction simulation, the hydrodynamic behavior and mechanical properties of vascularized channels in the perfusion process was discussed when the perfusion pressure, hydrogel concentration, and crosslinking density changed. The effects of perfusion pressure, hydrogel concentration, and crosslinking density on the flow velocity, pressure on the vascularized channels, and deformation of vascularized channels were analyzed. The simulation results provide a method to optimize the perfusion parameters of tissue engineering, avoiding the perfusion failure caused by unreasonable perfusion pressure and hydrogel concentration and promoting the development of tissue engineering culture in vitro.

关键词： three-dimensional bioprinting vascularized channels perfusion pressure hydrogel concentration fluid-structure interaction crosslinking density

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fluid-structure interaction during water hammer in a pipeline with different performance mechanisms of viscoelastic supports

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JOURNAL OF SOUND AND VIBRATION 2020年 487卷 115527-115527页

作者： Hosseini, Rahil Sadat Ahmadi, Ahmad Zanganeh, Roohollah Shahrood Univ Technol Dept Civil Engn Shahrood Iran Iran Univ Sci & Technol Dept Civil Engn Tehran Iran

The aim of this research is to model various types of viscoelastic supports and to investigate their effects on the fluid-structure interaction (FSI) during the water hammer in straight pipeline systems. Three performance mechanisms of viscoelastic supports are considered. The first is the viscoelastic supports with axial deformation, the second is viscoelastic supports with shear deformation and the third is the viscoelastic supports with both sliding and shear deformation mechanisms. The Poisson and junction coupling were taken into account as the main interacting mechanisms. The viscoelastic behavior of the pipe-wall and the supports was described by the generalized Kelvin-Voigt mechanical model. By providing boundary conditions for the different types of viscoelastic supports modeling at the valve location and along the pipe, the governing equations were solved using the full MOC method in the time domain. The results demonstrated that the use of viscoelastic supports with axial and shear deformation mechanisms are effective in the damping of the pressure head vibrations and reducing the displacement of the pipe-wall caused by FSI. The viscoelastic supports with the shear deformation mechanism exhibited better performance compared to those with the axial deformation mechanism. The results also showed that the behavior of viscoelastic supports with both sliding and shear mechanisms depended on the amount of frictional force in the supports. Using plates with an appropriate friction coefficient for the sliding viscoelastic supports caused a significant reduction in the amount of pressure head and displacement of the pipe-wall as well as considerable pressure head fluctuations damping compared to the performance of two other mechanisms of viscoelastic supports in a similar situation, especially in the elastic pipe. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： fluid-structure interaction Water hammer Viscoelastic support Sliding (friction) support Full MOC method

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Computational analysis of Nitinol stent-graft for endovascular aortic repair (EVAR) of abdominal aortic aneurysm (AAA): Crimping, sealing and fluid-structure interaction (FSI)

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INTERNATIONAL JOURNAL OF CARDIOLOGY 2020年第0期304卷 164-171页

作者： Jayendiran, Raja Nour, Bakr Ruimi, Annie Texas A&M Univ Qatar Mech Engn Program Doha Qatar Weill Cornell Med Qatar Doha Qatar

Objectives: We evaluate the crimping strain, sealing stress and contact forces on a Nitinol stent deployed in the aorta during endovascular aortic (or aneurysm) repair (EVAR) procedures. Nitinol shape memory effect (SME) is used. We also study the fluid-structure interaction (FSI) of the blood flow on the stented aorta. Methods: We employ Solidworks to generate a closed-cell honeycomb stent structure used to treat abdominal aortic aneurysm (AAA). We use the commercial Abaqus/Simulia finite element (FEM) simulation package to study the displacements and stresses experienced by the stent during the crimping phase and deployment into the aortic segment. The Nitinol stent is covered with Dacron, a popular graft material. We implement our own user-material (UMAT) subroutines to model the shape memory effect (SME) of Nitinol. The effect of the stent geometry is analyzed. We use the FSI analysis in Abaqus/Simulia to understand the effect of hemodynamic loading on the stent. Results: Results indicate that the crimping strain increases as the stent strut spacing increases. This is also the case for the radius of curvature. Maximum strains developed on the stent during crimping are in the order of 10%. Stresses exerted by the stent needed to completely seal the aorta are found to be below the yield stress values of Nitinol (700 MPa). Wall shear stresses (WSS) on the stented aorta are close to WSS obtained on the aorta alone. Conclusion: Using Nitinol's thermo-reactivity property as opposed to its superelasticity causes the stent-graft to deploy more gently. (C) 2019 Elsevier B.V. All rights reserved.

关键词： Stent-graft Crimping Sealing stress fluid-structure interaction Wall shear stress Nitinol

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fluid-structure interaction: Extended-FEM approach to solidification

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FINITE ELEMENTS IN ANALYSIS AND DESIGN 2020年 177卷 103425-103425页

作者： Caraeni, Daniela Casseau, Vincent Habashi, Wagdi G. McGill Univ Dept Mech Engn CFD Lab Montreal PQ H3A 2S6 Canada

The extended finite element method (XFEM) and the level set method (LSM) are applied to simulate the solidification phenomenon and the behavior of the liquid-solid phase transition. The temperature-based energy equation is loosely-coupled with the incompressible Navier-Stokes (INS) equations and solved by XFEM using the Stefan condition to express the energy conservation law for phase change. The INS equations are additionally supplemented with the Boussinesq approximation for the buoyancy force that drives the ensuing melt flow. The temperature, pressure, and fluid velocity are discontinuous at the interface, and the LSM implicitly captures its location. A modified abs-enrichment scheme (where abs stands for the absolute value function) is used for the weakly-discontinuous temperature field, and a sign-enrichment scheme is employed for the strongly-discontinuous pressure field. The penalty method imposes the interface temperature and velocity and allows for fluid-structure interactions. The numerical model is verified with several benchmark tests: 1D solidification, infinite corner solidification, Frank sphere, flow over a cylinder, as well as fin melting with non-constant density. Once the simulation results have been shown to be in good agreement with analytical solutions and results obtained with other methods, the present methodology is applied to a melting ice cylinder at a high Reynolds number.

关键词： fluid-structure interaction Extended finite element method Level set method Penalty method Stefan problem Solidification

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fluid-structure interaction in Transient-Based Extended Defect Detection of Pipe Walls

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JOURNAL OF HYDRAULIC ENGINEERING 2020年第4期146卷

作者： Zanganeh, Roohollah Jabbari, Ebrahim Tijsseling, Arris Keramat, Alireza Iran Univ Sci & Technol Dept Civil Engn Tehran *** Iran Eindhoven Univ Technol Dept Math & Comp Sci NL-5612 AZ Eindhoven Netherlands Jundi Shapur Univ Technol Dept Engn Dezful 64615334 Iran

This paper investigates the effect of fluid-structure interaction (FSI) on the efficiency of transient-based reflections analysis (TBRA) applied to the detection of extended deteriorations in a reservoir-pipe-valve system. A waterhammer-with-FSI solver, based on the method of characteristics (MOC) and the finite-element method (FEM), is used and validated against available numerical and experimental results. Analytical expressions for the magnitudes of pressure reflections caused by FSI are derived. They tell how the system parameters affect FSI. The results obtained for the considered situation reveal that both pipe wall vibration (FSI) and pipe wall deteriorations may affect transient pressure in a similar, and possibly indistinguishable, way. Neglecting FSI in TBRA would skew the estimated locations, lengths, and numbers of the deteriorations in systems with considerable pipe wall axial vibration, thus making TBRA a more complicated method in flexible pipe systems.

关键词： Waterhammer fluid-structure interaction Transient-based detection method Deterioration and blockage detection Pipeline supports

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Numerical simulation of flow past a triangular prism with fluid-structure interaction

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ENGINEERING APPLICATIONS OF COMPUTATIONAL fluid MECHANICS 2020年第1期14卷 462-476页

作者： Liu, Xu Gui, Nan Wu, Hao Yang, Xingtuan Tu, Jiyuan Jiang, Shengyao Tsinghua Univ Key Lab Adv Reactor Engn & Safety Minist Educ Inst Nucl & New Energy TechnolCollaborat Innovat Beijing Peoples R China RMIT Univ Sch Engn Melbourne Vic Australia

fluid flows around a pointed object, e.g. the flow around a triangular prism, are often encountered. In this study, numerical simulation of the flow around a triangular prism was carried out using COMSOL Multiphysics (R) software. Two cases were considered: the entire area of the triangular prism is fixed;and only the center is fixed. The first case is divided into three different flow models according to the flow state: the separation bubble model, the edge separation model and the attached flow model. The effects of different flow models on the lift coefficient, drag coefficient and Strouhal number were discussed from the perspective of fluid flow. For the second case, the triangular prism periodically rotates while the vortices are separated from the surface. It was found that a stable rotation stage exists after a certain period of time for prisms with different initial positions. The lift and drag coefficients of the triangular prism satisfy the jagged and sinusoidal variation.

关键词： Flow triangular prism fluid-structure interaction fixed constraint drag force flow-particle interaction

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Adjustment of CT-fractional flow reserve based on fluid-structure interaction underestimation to minimize 1-year cardiac events

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HEART AND VESSELS 2020年第2期35卷 162-169页

作者： Kato, Etsuro Fujimoto, Shinichiro Kumamaru, Kanako K. Kawaguchi, Yuko O. Dohi, Tomotaka Aoshima, Chihiro Kamo, Yuki Takamura, Kazuhisa Kato, Yoshiteru Hiki, Makoto Okai, Iwao Okazaki, Shinya Aoki, Shigeki Daida, Hiroyuki Juntendo Univ Grad Sch Med Dept Cardiovasc Med Bunkyo Ku 2-1-1 Hongo Tokyo 1138421 Japan Juntendo Univ Grad Sch Med Dept Radiol Tokyo Japan

The purpose of the study was to evaluate the optimal cut-off value of CT-Fractional Flow Reserve (CT-FFR) using fluid-structure interaction and how to adjust the CT-FFR's underestimation from a standpoint of minimize 1-year cardiac events. Subjects were 38 cases with 44 vessels in which stenosis of 30-90% was detected using one-rotation scanning by 320-row coronary CT angiography (CCTA) and invasive FFR (i-FFR) was performed within subsequent 90 days. CT-FFR was calculated using on-site from the multiple cardiac phases. A hypothetical 1-year cardiac event incidence was estimated using previous evidences when revascularization was decided based on CT-FFR. We assessed the optimal cut-off value of CT-FFR and how to correct the CT-FFR to minimize hypothetical cardiac events under four different disease prevalence (20%, 25%, 30%, 35%, and 40%). A total of 16 vessels had i-FFR <= 0.8. On per-patient basis, the sensitivity, specificity, positive predict value, negative predict value, and diagnostic accuracy of CT-FFR <= 0.8 vs CCTA > 50% to detect functional stenosis defined as invasive FFR <= 0.80 were 93.3% vs 73.3%, 73.9% vs 26.1%, 70.0% vs 39.3%, 94.4% vs 60.0%, and 81.6% vs 44.7%, respectively. For minimize 1-year cardiac events, the optimal cut-off value for more than 30% of disease prevalence was 0.80. However, the optimal cut-off value for 20, 25, and 30% was 0.54 in any cases. After the adjustment of CT-FFR using a formula of 0.3X + 0.634 for CT-FFR < 0.7 to counteract its underestimation, the % reduction of the events for 20, 25, 30, 35, and 40% at a 0.80 cut-off were 19.0%, 15.6%, 12.6%, 10.0%, and 7.7% respectively. It was reasonable to support that the optimal cut-off value was 0.80 in disease prevalence of more than 30% for minimize 1-year cardiac events. However, underestimation should be adjusted to reduce cardiac events, especially when disease prevalence is low.

关键词： Coronary CT angiography Fractional flow reserve fluid-structure interaction Minimize 1-year cardiac events Optimal cut-off value

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Seismic fragility analysis of AP1000 SB considering fluid-structure interaction effects

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structureS 2020年 23卷 103-110页

作者： Zhao, Chunfeng Yu, Na Mo, Y. L. Hefei Univ Technol Dept Civil Engn Hefei 230009 Peoples R China Hefei Univ Coll Econ & Management Hefei 230601 Peoples R China Dalian Univ Technol State Key Lab Struct Anal Ind Equipment Dalian 116024 Peoples R China Univ Houston Dept Civil & Environm Engn Houston TX 77021 USA

AP1000 nuclear power plant has an advanced passive cooling system with a vast water tank located above the shield building, which may affect the seismic performance of the structure. This paper conducts a fragility assessment of shield building and considers the fluid-structure interaction (FSI) effect on the damage of the shield building. Arbitrary Lagrangian Eulerian algorithm is applied to calculate the FSI and eight cases of water levels are considered. Three different fragility analysis methods, namely linear regression, quadratic regression and truncated maximum likelihood estimation, are adopted for assessing the seismic vulnerability of shield building. It is indicated from the results that the regression and the truncated maximum likelihood estimation are close to each other. The maximum likelihood estimation not only can effectively save the computational cost, but also can assure the reasonable calculated results. It is observed that different water levels have the individual probabilities of failure, and case 6 has the smallest probability of failure with a more considerable seismic reduction, whereas the case 1 and case 2 have the higher failure probabilities. The fragility analysis framework can thus be applied for evaluating the vulnerability of shield building under earthquakes considering the FSI effect.

关键词： Vulnerability assessment fluid-structure interaction Quadratic regression Maximum likelihood estimation Shield building

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